/Engine/Source/Runtime/SlateCore/Public/Styling/SlateStyleRegistry.h
Iterate all the slate style known to this registry
true where to loop completed, of false if it was terminated by the predicate
static bool IterateAllStyles ( const [TFunctionRef](API\Runtime\Core\GenericPlatform\TFunctionRef)< bool(const [ISlateStyle](API\Runtime\SlateCore\Styling\ISlateStyle) &)> & Iter )